Centrifugal speed regulator



June 2 F. W. MERRILL CENTR'IFUGAL SPEED REGULATOR Filed Jan. 19, 1922Patented June 2, 1925.

UNITED STATES PATENT OFFICE.

FRANK w. MERRILL, or ms'r omen, NEW JERSEY, ASSIGNOR To WESTERN ELEC-rnrc COMPANY, INCORPORATED, or NEW YORK, N. Y., A CORPORATION or NEWYORK.

CENTRIFUTGAL SPEED REGULATOR.

Application filed January 19, 1922. Serial No. 536,301.

To all whom it may concern:

Be it known that I, FRANK' W. MERRIL a citizen of the United States,residing at East Orange, in the county of Essex, State of New Jersey,have invented certain new and useful Improvements in Centrifugal SpeedRegulators, of which the following is a full, clear, concise, and exactdescription.

This invention relates to improvements in motor speed regulators andparticularly to speed regulators which are responsive to centrifugalforce.

An object of the invention is to provide a means for regulating thespeed of electrical motors, which is instantaneously responsive tovariations of the motor speed and also to the electrical variations ofthe moto circuit.

Another object of this invention is to provide a compensating device forspeed rogu lators which will anticipate changes in motor speed which aredue to electrical variations in the motor circuit and which "willprevent such speed changes from taking place .by causing the electricalvariations to make a mechanical change in the adjustment of theregulator which will ofiset their effect, permitting the speed to remainconstant.

More specifically the invention relates to a device which is to beattached to centrifugal motor speed regulators to increase the accuracyof operation thereof. This device consists of a solenoid which ismounted to rotate with the revolving portion of the speed regulator andcooperates with a plunger mounted upon the flexible contacting member ofthe regulator to efi'ect the distortion of this member. The solenoid ismade 40 responsive to either the voltage or the load of the motorcircuit as one or the other of these circuit characteristics happens tobe subjected to the larger variation in value, or

it may be made responsive to both. The inaccuracy in the operation ofspeed regulators'which this solenoid is designed to overcome ismechanical in nature. Centrifugal speed regulators for electric motorsgenerally consist of two contacts one fixed and the other flexiblymounted and movable into or out of engagement with the fixed contact ainst the resistance of a spring. Assume, fii r example, that theregulator is connected across a resistance in serieswith the shu r1tfield of a motor which is subject 6 to variations in terminal voltage,load changes, or a combination of the two; and that it is desired to.hold the speed of the motor, accurately at a certain value under allvarying conditions. The usual. method of setting the speed is to adjustthe spacing of the contacts so as to obtain the desired speed under theconditions of half load and intermediate voltage. At the time of lightload and maximum voltage the speed (with the regulator functioning) mayrise any: where from A of 1% to 2% above this point, and at the time offull load and minimum voltage may fall the same percentage below thedesired value. The primary cause of 7 this variation is due to themechanical characteristic of the regulator. Variable strain ordeflectionof the resilient arm holding the movable contact is required to producethe and at the time of full load and minimum variations in the fieldcurrent required. If the motor is started slowly from rest and graduallybrought up to speed (the regulator gap being set) the flexibly mountedcontact is gradually deflected by the increasing centrifugal force ofthe weight through a greater and greater angle (but without vi- Ibration) until at aspeed slightly higher than the regulating point ittouches the fixed contact, short circuiting the resistance in serieswith the shunt field and causing an abrupt drop in. speed. The

spring, however, immediately opens the contact causing a sudden increasein speed. The opening and closing of the contacts in this manner setsthe flexibly mounted arm into rapid vibration through a small are, thechanges in motor speed necessary to maintain this vibration being almostnegligible in the case of a well designed regulator. If the gap iscorrectly adjusted, then the movable contact in its vibrations willshort circuit the field resistance for just the right length of time tobring the average field current to a value that will hold the correctspeed under intermediate conditions of voltage and load. Suppose thatthe condition now changes to that of maximum voltage and light load. Ifthe shunt field current could be increased to just the right value themotor speed could be held exactly at the point of setting. In order forthe regulator to increase the field current. however, it is necessaryfor the flexibly mounted arm to be deflected a little further so as tobring the contacts closer together. This is equivalent to moving theentire vibrating arc of the flexible contact closer to the fixed contactso that the flexible contact in its vibrations will be stopped and heldagainst the fixed contact for a larger percentage of the time. \Vithoutany compensating device this increased deflection can only be broughtabout by an increase in speed of 1 to 2% as mentioned above but if thevibrating arm could be deflected this extra amount by some other forcethen it would not be necessary for the speed to increase at all. Asolenoid actuated either by the line voltage or the load current mountedso as to rotate with the moving element of the regulator can be used tosupply this corrective force. Such a solenoid can be made strong enoughto over-compensate, that is,

*to cause the motor to slow down with increased line voltage or to speedup with increased load if desired and by adjusting the strength of sucha solenoid by external resistance almost perfect speed regulation may beobtained.

In addition to a plain shunt (voltage) or series (load) coil, thesolenoid may be fitted with both a shunt and a series winding. In thiscase, the shunt winding is generally designed to have a greatermagneto-motive force than the series winding even at the time of lowvoltage. The series coil is differentially connected and both load andvoltage compensation is secured simultaneously.

I11 the drawings, Fig. 1 is a diagrammatic illlustration of a motorcontrolled by a centrifugal speed regulator provided with a compensator.

Fig. 2 is a schematic view showing a regulator provided with acompensator having differentially wound voltage and load coils.

Referring to the drawings in detail, a centrifugal speed regulator,which may be of the type disclosed in Patent No. 1,494,927, datedMay-20, 1924, is associated with a shunt wound motor 1 for controllingits speed. The regulator has a stationary annular contact member 2mounted upon a rigid support 3. Anupwardly extending, hooked arm 4:provides a means for electrically connecting the member 2 to a conductor5. A revolving contact member mounted adjacent annular member 2 forcooperation therewith comprises a bar 6 yieldingly attached to aresilient member 8 secured to a bushing 9 which is keyed to motor shaft7. A weight 10 offset from one end of the bar 6 moves outwardly from themotor'axis 7 under the influence of centrifugal force thereby causingdeflection of bar 6 and distortion of resilient member 8 moving contactpoint 11, mounted on bar 6, in a direction parallel to the motor axis 7into wiping engagement with stationary annular contact member 2. Theengagement of revolving contact 11 and stationary annular contact 2closes a clrcuit from a battery 12 or other suitable current sourcethrough a motor field 13 which may be traced as follows: positive poleof battery 12, conductor 14, brush 15, slip ring 16, conductors 25 and17 bar 6, contacts 11 and 2, arm 4, conductor 5, shunt motor winding 13,conductors 30 and 18 to negative pole of battery 12. When regulatorcontacts 11 and 2 are separated, on the other hand, as occurs at reducedmotor speeds, a second circuit for the motor field 13 is completed whichis traced as follows: positive poleof battery 12, conductors 14 and 19,a resistance 20, conductors 21 and 5, shunt motor field 13, conductors30 and 18 to negative pole of battery. The regulator, therefore, bycutting resistance 20 into and out of circuit with shunt motor field 13,operates to permit increased current to flow through said winding 13when a decrease in speed is desired and decreased current when anincrease in speed is desired. 7

The compensating device comprises a solenoid 22 mounted upon an arm 23integral with and extending radially from bushing 9 for rotation withmotor shaft 7 to which bushing 9 is keyed. This solenoid 22 may beenergized across the battery leads, in series with one of them, or by awinding which combines these two methods. In Fig. 1, solenoid 22 isacross the battery leads and is therefore responsive tothe batteryvoltage. Its energizing circuit may be traced as follows: positive poleof battery 12, conductor 14, brush 15, slip ring '16, conductor 25,solenoid 22, conductor 26, slip ring 27, brush 28, conductor 18 tonegative pole of battery 2. A plunger 29 mounted upon revolving contactbar 6 of the regulator moves within the solenoid 22 in response to thevoltage of the battery leads, its movement serving to increase ordecrease the deflection whiclf the bar 6 receives as a result of thecentrifugal action upon its weighted end.

Fig. 2 shows a modification of the inven tion in which the regulator iscorrected for voltage and load by Ineansof a solenoid 22 which isprovided with two differential windings 31 and 32. The voltage winding31 is positive in its action tending to'close the regulator contactswhen energized; whereas the load winding 32 has a bucking effect uponthe voltage winding tending to open the regulator windings and to allow.the motor speed to increase. The circuit of. series windin 32 may betraced from positive pole of attery 12 through conductor 14, brush 33,slip ring 34, conductor 35, series Winding 32, conductors 36 and 37,slip ring 16, brush 15, conductor 38, armature 1, conductors 39 and 18to negative pole of Ion l mu;

tive pole of battedy 12', conductor 14,

brush 33, slip ring 34, conductor 35, series winding 32, conductors 36and 37, slip ring 16, brush conductor 38, armature 1, conductors 39 and18 to negative pole of battery 12'. Shunt field 13 of motor 1 isnormally energized through a circuit including series resistance whichmay be traced from the positive pole of 12', conductor 14,

"brush 33, slip ring 34, conductor 35, series winding 32, conductors 36and 37, slip ring 16, brush 15', conductors 38 and 19, series resistance20, conductors 21 and 5, shunt field 13', conductors and 18 to negativepole of battery 12'. \Vhen an increase in line voltage or a decrease inline load occurs which would tend to increase the speed of the motor,differentially woundsolenoid';

22' attracts its plunger (or core) 29' thereby increasing the angle ofdistortion of the rotating member 6 diminishingthe distance betweenrotating contact 11' and stationary contact 2. As these contacts arefinally brought into engagement their closin shortcircuits resistance20" and causes field wind ing 13' to be energized over the followingcircuit: positive pole of battery 12', conductor 14', brush 33, slipring 34, conductor,

18"to negative pole of battery 12.

35, series winding 32, conductors 36 and 17',

- vibrating contact member 6', contact point .11, stationary contact 2',arm 4', conductor 5', shunt winding 13, conductors 30, and The solenoidis thus made to anticipate changes in the speed of the shunt wound motor1 which would-otherwise result from an in creasing line voltage or adecreasing load;

: What is claimed is:

1. A. source of electric energy, an electric motor and a regulatortherefor, said regulator'comprising a solenoid mounted on the shaft ofsaid motor and revolving therewith and ada ted to be energized from saidsaid source of ener source b energy, a core for said solenoid movabletherein in response to variations. in a vibrating contact also mountedon an shaft-and in cooperative 'relation with said core and a fixedcontact with which said vibratingcontact is adapted to engage inresponse to speed changes in the motor and variationsin said source.

3 2. A motor and a regulator therefor,said regulator'comprising arevolving solenoid,

a core therefor, a vibrating contact associated with said" core and afixed contact revolving with said with which said vibrating contact isadapted to' engage to regulate said motor in response to speed changesof the motor and electrical variations in the motor circuit.

3. An electric motor, a, circuit therefor, a centrifugal speedregulating device therefor and a compensating device associated withsaid centrifugal device comprisingan electromagnet mounted on andrevolving with the shaft of said motor and energized from said circuitadapted to cooperate with. said centrifugal device to regulate saidmotor when electric variations occur in said circuit.

4. An electric motor, a circuit therefor, a centrifugal speed regulatingdevice therefor and a compensating device associated with saidcentrifugal device comprising an electromagnet mounted on and revolvingwith the shaft of said motor and energized from said circuit adapted tocooperate with said centrifugal device to regulate said motor riteaa'rawhen voltage changes occur in said circuit.

.to cooperate with said regulating device to control the speed of saidmotor.

6. An electric translating device including an energizing circuit and acircuit. to be controlled, means comprising a fixed and a movablecontact associated with said device for making and breaking said circuitto be controlled, said movable contact operating in response'tomechanical variations in said translating device during the operationthereof and an electromagnetic auxiliarydevice for further controllingsaid movable contact, said auxiliary device being 7 adapted to operatein response to electrical variations in said energizing circult.

5. An electric motor, a centrifugal'speed 7. A translating device, anenergizing cir-' cuit therefor, means for controlling the energlzatlonof sald device, sald means comprismg a fixed contact and a vibratingrotating a helix 1 contact cooperating therewith, mounted for rotationwith said rotating contact, a core, operatively associated with saidrotating contact and movable relativel to said helix whereby theposition of sai rotating contact is effected.

8.- A translating device having an enercomprising a fixed contact and amovable 'gizing circuit and a regulating circuit, means 7 and a solenoidassociated with the movable contact of the first mentioned meansresponsive to voltage variations in the circuit of said translatingdevice, associated with said filst mentioned means and cooperating therewith said means, said device having one winding responsive to thevoltage of said energizing circuit and a second winding cooperating withsaid first winding, 531(10880- 0nd winding being responsive to the loadin said energizing circuit.

10. A translating device having an energizing circuit and a regulatingcircuit, means responsive to centrifugal force for making and breakingsaid regulating circuit and a solenoid associated with said firstmentioned means for opening and closing the-regulating circuit, saidsolenoid having a winding responsive to the voltage of-said energizingcircuit and a second winding differentially wound with respect to saidfirst winding, said second winding being responsive tothe load in saidenergizing circuit.

11. In combination, an electric motor and a regulator thereforresponsive to speed changes of the motor and variations in the electriccurrent supplied to said motor, said -regulator comprising a vibratingcontact member and an electromagnetic device both resiliently mounted onthe shaft of said motor, and a stationary contact member in cooperativerelation with said vibrating contact member. Y

12. In combination, an electric motor and a regulator thereforresponsive to speed changes of the motor and variations in the electriccurrent supplying said motor, said regulator comprising a vibratingcontact member and an electromagnetic device, both fixed to andrevolving with the shaft of said motor, and a second contact memberfixedly mounted and in cooperative relation with said first contactmember, said electromagnetic device being controlled by saidcurrentsupply to close said contacts.

13.111 combination, an electric motor, a centrifugal speedregulating'device therefor including a fixed and a vibrating contact,and compensating means associated therewith, comprising anelectromagnetic device controlled by the current supplied to said motorand revolving with the shaft thereof to move said vibrating contact intoengagement Withsaid fixed contact.

In witness whereof, I hereunto subscribe my name this 16th day ofJanuary A. D., 1922.

FRANK IV. MERRILL.

